The most popular cosmetic procedure in the world is wrinkle reducing injections with neurotoxins or the friendlier term, neuromodulators. The injections work by reducing the activity of the muscles they are injected to, there by resulting in less movement and less dynamic wrinkles. Static wrinkles, ones that appear at rest, are less affected by these injections, but over serial treatments, improve as well.
The history of neuromodulators dates to the isolation of the botulinum toxin, the cause of botulism, in the 1928. It was later refined and made commercially available for injections in the 1989 and initially FDA approved for strabismus, lazy eye. Soon thereafter, blepharospasm, spasm of the muscles around the eye, treatments were approved. The team of Carruthers and Carruthers observed that during blepharospasm treatments, the wrinkles around the eye, crows feet, were also improved. Studies were later performed on the frown lines, and FDA approval for cosmetic use was achieved in 2002.
There are currently 3 FDA approved neuromodulators of botulinum toxin A for cosmetic use: Botox, Dysport, and Xeomin. They all work similarly by blocking the acetylcholine release at the neuromuscular junction. Each brand has their own definition of what a unit dose is, so this can be confusing to both the practitioner and the patients. The differences between the 3 is the associated inactive protein, or absence of this protein in the case of Xeomin. Studies have shown that once the drug powder is mixed with water or saline in the provider’s office, the inactive protein disassociates almost immediately. Why then, are there differences in clinical outcomes between the 3 neuromodulators?
There is a recent comparison of the active protein molecule in the 3 products dosing in the glabella. The study looked at the FDA approved doses for frown lines – glabella. A very interesting finding was that there was 0.27ng in Dysport using the 50u dose vs 0.18ng in Botox’s. Xeomin was a distant 3rd coming in at 0.08ng with their 20u dose. In essence, patients are receiving a stronger dose when using Dysport when compared to Botox or Xeomin.
It’s long been established that Dysport seems to be effective (in 1-2 days) sooner than Botox (3-4 days) but the reason was never clearly elucidated. It’s also well known that higher dosing of any of the neuromodulators will lead to longer durations of action. This higher level of active protein with Dysport can explain the clinical phenomenon of quicker onset and longer duration.
One other topic needing addressing is the myth of higher diffusion with Dysport vs Botox. Diffusion or spread, is a result of dosing, volume, speed of injection and not a function of the neuromodulator. As stated before, when reconstituted, all the products are free of their associated proteins and only consist of free, active protein. We now know that Dysport has more active protein in their approved dosing, so to compensate, lower volumes must be used for reconstitution. The author’s recommended reconstitution for Botox is 2cc and for Dysport is 1.5cc for the glabellar injections. When diffusion or spread is desired, larger volumes can be used.
With the recent comparison study of active protein in the dosing schemes of the 3 commercially available neuromodulators, it is easy to see why Dysport should be the standout choice. Dysport gives more effective treatments because of the higher active protein, leading to quicker onset and longer duration than Botox and Xeomin. Pricing is usually less with Dysport, so it becomes a “no brainer” 1st choice for Dr. Weiner’s practice.